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INSTANTANEOUS BLOOD LOSS DETERMINATION DURING THORACIC SURGERY
INSTANTANEOUS BLOOD LOSS DETERMINATION DURING THORACIC SURGERY Robert Klo pstock, MD' J * Harry H. Lei/een, MD. ** (by invitation) J and P. I. Levitan, MD.*** (by inuitation}, Brooklyn, N. Y. and duration of present-day surgery, in general, and of T thoracic and cardiovascular surgery, in particular, would not be possible without adequate blood replacement. As magnitude and duration of surgical H E MAGNITUDE
procedures expand, the volume of operative blood loss increases, necessitating replacement of larger and larger amounts of blood. Anatomic structures dealt with in thoracic and cardiovascular surgery carry the risk of brisk hemorrhage on occasions and the demand of speedy restoration of the circulating blood volume. How then may one best maintain an adequate blood volume and at the same time prevent undertransfusion or eireulatory overloading? The work of Ebert and Stead- clearly indicates that during the course of blood loss in normal donors there is no gradual decrease in blood pressure and pulse rate. These authors state, "the onset of collapse was sudden. Until it occurred, the subject had no complaints. In three subjects collapse developed from 1 to 4 minutes after venous suction was completed. The compensatory mechanism appeared to break down suddenly cven though no more blood was being removed and the position of the subject had not been changed." This fact is well illustrated by a diagram which has been adapted from Barcroft and others" (Fig. 1) to demonstrate the changes in vital signs during the brisk hemorrhage in a normal donor. The blood pressure which starts in the neighborhood of 120 does not fall, the pulse rate rises but little, and yet the cardiac output continuously diminishes. It is only when compensation fails that the blood pressure drops suddenly. This shows that the blood pressure and the pulse rate cannot be relied upon as an index of adequate replacement. Neither the rise in pulse rate nor the fall in systolic pressure makes its appearance until the volume of blood loss is greater than can be compensated for by vasoconstriction. This usually does not occur until after 800 to 1,500 c.c, of blood is lost, if the From the Department of Surgery, Veterans Administration Hospital, Brooklyn, N. Y., and State University of New York, Downstate Medical Center, Brooklyn, N. Y. Read at the Thirty-ninth Annual Meeting of The American Association for Thoracic Surgery at Los Angeles. Calif., April 21-23, 1959. ·Chief, Thoracic Surgical Section, Veterans Administration Hospital, Brooklyn, N. Y., and Clinical Associate Professor of Surgery, N. Y. S. U. ··Chief, Surgical Service, Veterans Administration Hospital, Brooklyn, N. Y., and Associate Professor of Surgery, N. Y. S. U. ···Resident, Surgical Department, Veterans Administration Hospital, Brooklyn, N. Y.
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BLOOD LOsS DETERMINATION DURING SURGERY
VoL 38, No.6
December. 1959
patient is a well nourished and hydrated adult. Although venous pressure is of some value in determining the extent of blood loss, it becomes valueless during rapid bleeding and rapid replacement. During severe hemorrhage the sudden replacement of blood may fail to bring about a recovery in the hemodynamic alterations even when replacement has been of the proper amount. There have been various explanations for this failure of transfusion to prevent the disturbances in hemodynamics, some of which have been ascribed to the high citrate concentration of bank blood. The citrate in blood enhances the action of potassium by removing its ionic antagonist, the calcium. The potassium concentration of bank blood rises to 25 mEq. per liter by the end of 2 weeks. The rapid infusion of this bank blood may induce cardiac arrest or a state not unlike that of forward circulatory failure. It is under these circumstances that
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Fig. l.-The course of events during rapid venous section of a normal donor is charted. Blood pressure (B.P.) falls precipitously from 120 to 40 mm. Hg. The heart rate (H.R.) does not rise above 100. The cardiac output (0.0.) falls continuously. The total peripheral resistance (T.P.R.) rises until decompensation occurs. Right auricular pressure (R.A.P.) falls continuously during the bleeding.
venous pressure will fail to differentiate between overtransfusion and forward circulatory failure induced by high potassium concentration of bank blood. It is, therefore, obvious that if accidents are to be avoided during surgery entailing massive blood loss that the amount of loss must be continuously measured during the operative procedure and exact replacement made for the amount which is lost. Since the first study of blood loss during some of the most common operations was reported by Gatch and Little" in 1924, many investigators have made extensive measurements of operative blood loss in the various fields of surgery
748
KLOPS1'OCK, LE VEEN, LEVITAN
1.Thoracic and Cardiovas. Sura.
and concluded that volume lost was always greater than the surgeon estimated and that the circulatory volume may be decreased considerably before clinical shock is noted. Great credit should go to Wangensteen- for having suggested (1942) the relatively simple and accurate method for determining operative blood loss as it occurs by weighing the dry sponges before and after their use and thus calculating the blood lost during surgery. In the field of thoracic surgery, White and Buxton," then Miller, Gibbon, and Allbrit.ten," made very valuable studies of blood loss during the various major thoracic procedures. Gibbon" and his associates pointed out that they were unable to estimate the amount of blood which had been lost and the amount which should be replaced by observing the vital circulatory signs. Operative blood loss has previously been determined by both the gravimetric and the colorimetric methods. Blood volume studies were done by the dye dilution method, according to Gibson and Evans," and by radioactive tagging of blood components, and the blood loss has been calculated in these ways. However valuable these methods are, they are not very suitable for the routine and everyday evaluation of blood loss in the operating room when extensive procedures of long duration are carried out. The possibility of using the phenomenon of electrical conductivity in the determination of operative blood loss has been investigated by Harry H. LeVeen. 7 The conductivity method is based on the fact that blood.is a solution of almost constant electrolyte composition. Even in "low salt syndrome" and other more serious disease states, the total sodium does not vary by more than 10 to 20 c.c. mEq. per liter. The extent of blood loss can therefore be assessed by measuring the quantity of lost electrolytes. The electrical resistance of a solution decreases with increasing electrolyte concentration. More concentrated solutions of electrolyte will allow for greater passage of current according to Ohm's law. If blood is added to water in varying concentrations, a direct proportional relationship between concentration of blood and conductance results. Since small changes in conductance can be accurately measured with a Wheatstone bridge, the change in conductance produced by the the addition of blood to known volume of water can be determined precisely. With a suitable Wheatstone bridge and proper temperature compensation, determinations are accurate to 0.5 per cent. LaVeen," utilizing the discussed principles, carried out extensive preliminary experiments and devised an apparatus, the blood loss monitor, which calculates and instantaneously registers all blood delivered into it. DESCRIPTION OF THE BLOOD LOSS MONITOR
The apparatus consists of a large stainless steel tub with an agitator which continuously extracts the electrolytes from the sponges and clots. A suction pump transfers blood from the operating table directly into the tub (Fig. 2). This procedure makes possible the addition of blood loss taken up via suction as well as from bloody sponges. Since conductivity increases with increasing temperature of the solution, automatic temperature compensation was
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December, 1959
BWOD LOSS DETERMINATION DURING SURGERY
749
accomplished by introducing a thermistor into one arm of the conductivity bridge. The thermistor assumes the temperature of the water in the reservior and changes the resistance of one arm in the bridge to compensate for the decreasing resistance of the solution at increased temperatures, It was desirable to have a direct reading instrument which would obviate the difficulties of manually balancing the conductivity bridge. Hence, a servomechanism was coupled with the conductivity bridge. The servomotor continuously brings the bridge to the null balance point. Instantaneous and continuous detection of conductivity changes are made. The conductivity bridge and cell must be specially constructed to operate on low voltages in order to minimize polarization and, at the same time, maintain its sensitivity. All components of the machine are constructed to meet explosion proof requirements
Fig. 2.-A photograph of the blood loss monitor is shown in simulated use. The bloody sponges are dropped in the open tub. The suction is connected to the side of the apparatus. The dial face can be seen.
for use in an operating room. 'I'he bridge is calibrated in cubic centimeters of blood rather than in solution conductance (the unit of electric conductivity) Blood loss is measured in increments of 100 c.c. up to 8,000 c.c. and with possible estimate of 25 to 50 c.c, within the increment. There is also an arrangement to measure small volume of blood loss from 0 to 800 c.c. to be used in surgery of children. This dial can be read with an accuracy to 20 coco and estimated to 10 c.c. within the increment (Fig. 3) This range can be put into operation by turning the proper switch. A centrifugal pump empties the tub following usage and the 0
0
750
KLOPSTOCK, LE VE E N, LEVITAN
J. Thoracic an d Cardiovas. Surg.
t ub can h e rapidly emp t ied into a regular sink and refilled so that losses g rea ter th an 8,000 c.c. can be measured. The machine is clea ned with a chlorin ated det e r gent foll owing us e a n d rinsed wit h t a p water . A st a inless steel mea sure is u sed to m ea sure t he initial quantit y of tap wa t e r placed in the tub. F'i xed resistances with push but ton s a re in cluded so t hat th e
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Fig. 3.-The dial face t ogether with the range switch is illustrated In detail. switch Is in the "a dult" positi on readings a re mad e on the oute r circula r scale. switch is In the "ch ild" positi on the inn er cir cula r sc a le Is used for reading.
When the W hen the
POWER SUPPLY
Fi g. 4.- Sche matlc di a gram of the a utoma t ic blood loss meter. A measured volume of d is t illed water ( 25,000 c.c.) is a dded to the tub. An a gitato r ex t r act s elect r olytes f rom the s pon ges, la p pads. a nd clots. A s ucti on appara t us t ransf e rs blood from the ope rati ve site to the tub, Auto ma tic temperatu re com pensa tio n is accomplished with a thermistor wh ich form s one arm of this bri d ge. The cond uc t ivi ty cell is al so shown. A servomot or continuou sly keeps the brid ge a t the null balance po int . The dial of the meter Is calibrated directly In cubic centimeters of blood. Sponges a nd laparot omy pads a r e held in a stainless steel basket indicated by br oken lin e inside conta iner. ca lib r a t io n of t he ma chi ne ClUJ be pre-t es ted before usc. A nu ll b alance of 0 c.c. of bl ood is automatically a ccomplished by u sin g t ap w a t er of low con d uc tivity or di stilled water. Cor rect ion f or t he ini t ia l conductiv ity of t he water is then un necessary . A sche ma t ic dr awing of the instrumen t is sho wn i n F ig. 4.
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BLOOD LOSS DETERMINATION DURING SURGERY
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Remarks.-It is evident that sodium chloride solutions cannot be used for irrigation purposes or to moisten sponges and pads. unless a definite measure of the amount of sodium chloride used is made and subtracted from the final total of indicated blood loss. We use a solution of 2.5 per cent glucose for moistening laparotomy pads for irrigation. Since glucose is a nonelectrolyte, it does not interfere with the readings. OBSERVATIONS
The blood loss monitor was used in 62 patients who underwent major thoracic and cardiovascular surgery.* In Table I, the observed minimum and maximum blood loss values are tabulated for each type of operation and the calculated averages are noted. These are approximately equal to those reported by other authors, notably by Miller, Gibbon, and Allbritten." Blood loss sustained up to the opening of the pleural cavity ranged 150 to 750 e.e. with an average of 364 C.c. It should be stressed that there was no need in any case for additional blood replacement after completion of the surgical procedure if blood replacement was made according to the indication on the monitor. In all cases there was less than 1.2 Gm. change in the hemoglobin value on the first to the fourth day as compared with preoperative values. Thornton and Adams" pointed out that the amount of hemoglobin tends to drop postoperatively in those cases where blood replacement has been inadequate. This postoperative drop in hemoglobin value described by Thornton and Adams did not occur in our cases in which the blood replacement was carried out under the guidance of the blood loss monitor. There were only 2 cases (No.1 and No.2) in which shock occurred during surgery, and these observations are described fully because of their study value. COMMENT ON ILLUSTRATIVE CASES
In this instance it was decided to compare the accuracy of the anesthetist's clinical estimate to blood loss registered by the monitor. Therefore, the "dial indication" of blood lost was unknown to him at the time vital signs had changed. I.-Lobectomy for Carcinoma With Chest Wall Involvement.The patient was a 39-year-old man with a round tumor in the right upper lobe. On exploration of a carcinoma, it appeared that it was anatomically resectable by means of an upper lobe resection, even though the tumor-bearing part of the lobe was densely adherent to the parietal pleura in a circumscribed area. In addition, the entire upper lobe was attached by vascular adhesions to the parietal pleura. Therefore an extrapleural dissection was carried out. This patient exhibited an unusual degree of oozing over a prolonged period of time. During the procedure, the degree of blood loss was not appreciated by the anesthetist until the vital signs changed. At this time 3,500 c.c. of blood loss was registered while only 2,000 c.c. had been replaced (Fig. 5). The known deficit was corrected gradually and the patient's condition returned to normal. Total blood loss and replacement for the operation was 7,000 c.c. In the postoperative period, no additional blood replacement was necessary. CASE
This observation illustrates the wide discrepancy between clinical impression and accurate measurement of blood loss. It is in such cases, when the blood loss is small hut continuous, that undertransfusion is common. ·See Addendum.
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753
BLOOD LOSS DETERMINATION DURING SURGERY
Vol. 38, No.6
December, 1959
RIGHT LOBECTOMY CA WITH CHEST WALL INVOLVEMENT
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Fig. 5.-Illustrates not only the ease of management of a patient who during surgery had gradual blood loss of 7,000 c.c, with change in the hemodynamics but also the facility with which known large deficits can be readily corrected. CASE
2.-Mitral Comsnissurotomq.s-:
The patient was a 37-year-old white man with mitral stenosis. During the otherwise uneventful procedure there was a sudden loss of 1,200 c.c. of blood following tear of the left atrium and superior pulmonary vein. Blood pressure was unobtainable for a short period of time, but returned to normal after replacement of the indicated volume. The patient did well following surgery and no further blood replacement was needed (Fig. 6).
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Fig. 6.-Brisk blood loss precipitating shock during cardiac surgery is easily managed by monitoring and replacing the blood loss as it occurs.
754
J. Thoracic and
KLOPSTOCK, LE VEEN, LEVITAN
Cardiovas, Surg.
When blood loss is sudden and massive one may "get lost" in the management of replacement if it is based on clinical estimate. It is in such cases that overtransfusion, most commonly, and cardiac arrest, occasionally, are induced. The train of events substantiates also the experimental data on normal donors which indicate that vital signs do not change until considerable blood has been lost and only then they change suddenly.
H ypothermia.The increasing use of hypothermia poses problems for both surgeon and anesthesiologist. Not only does hypothermia render the vital signs valueless, but it also enhances the tendency toward cardiac arrest. During hypothermia, RESECTION OF ANEURYSM OF THORACIC AORTA WITH HYPOTHERMIA
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patients tolerate blood loss very poorly and the blood volume is restored very slowly after hemorrhage. This is partly brought about by a fall in the osmotic pressure of the plasma protein during hypothermia. Under these circumstances fluid cannot be rapidly mobilized from the tissue spaces. The instantaneous determination of blood loss was of considerable aid not only in thoracic surgery, but in all surgery performed with hypothermia. The following case report illustrates the usefulness of monitored blood loss in cardiovascular surgery carried out under hypothermia with necessarily hypotensive blood pressure levels and altered pulse rate. CASE
3.-Excision and Repbaoemcnt of Descending Thoracic Aorta.-
The patient was a 42-year-old white man with a large fusiform aneurysm of the descending thoracic aorta. At exploration the dilatation was found to extend from just distal to the left subclavian artery to a point just above the diaphragm. Under hypothermia a
BLOOD LOSS DETERMINATION DURING SURGERY
Vol. 38, No.6
December, 1959
755
Teflon prosthesis was used to bypass the aneurysm which was then resected; the prosthesis was left as a permanent bypass. There was no dramatic blood loss during the 10-hour procedure, but after replacing the volumes of blood indicated by the monitor, it was found that 6,200 c.c. of blood had been lost by continual ooze. The patient had an uneventful postoperative course and no further blood replacement was necessary (Fig. 7).
In the properly monitered case, blood deficit and overtransfusion do not occur if loss and replacement are checked periodically during the course of prolonged surgery. Hourly check should be considered the minimum interval during the uneventful progress of an operation. A typical chart of monitored blood loss is shown in Fig. 8. RIGHT
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Fig. B.-The matching of blood replacement to blood loss is shown in a typical intrathoracic surgical procedure. GENERAL COMMENTS
In the foregoing, data are presented to document the value of an apparatus, the blood loss monitor, for accurate determination of blood loss during surgery as it occurs. The construction and function of the apparatus is based on the fact that the blood is a solution of almost constant electrolyte composition. The extent of the blood loss is assessed by measuring the quantity of lost electrolytes. _ Since the characteristics of blood as an electrolyte are utilized as a measurement of blood, all the factors affecting conductivity in blood must be reckoned with.
Nonelectrolyte in high enough concentration will effect a reduction in conductivity. The usual concentration of glucose and nonprotein nitrogen in blood do not produce a perceptible change. Serum protein and hemoglobin do influence conductivity in an ideal way. For each gram per cent deficit in plasma
KLOPSTOCK, LE VEEN, LEVITAN
756
J. Thoracic and Cardiovas. Surg.
protein, conductivity increases approximately 2 per cent. A blood loss of 100 e.e. in a patient with a gram per cent deficit in plasma protein would appear as a loss of 102 C.c. This would cause the patient to be overtransfused by 2 per cent. A change in hematocrit from 50 to 5 will register approximately 20 per cent increase in loss. An anemia of 50 per cent would bring about an overreplacement of blood loss by an amount slightly in excess of 10 per cent. The method makes moderate corrections for severe hypoproteinemia and anemia. Open Ifeart Surgery.- vVe have not yet had the opportunity to usc the blood loss monitor in open heart surgery, but it seems apparent that such an apparatus could be of inestimable value. The accurate determination of the blood lost before the perfusion begins could be accomplished with ease. During perfusion all blood lost from the' oxygenator-patient-circuit must be accurately known so that correct volume of blood may be maintained in the patient and the perfusion terminated with the patient in normovolcmie state. In infants, of course, this assumes even greater importance since small amounts of blood represent larger proportions of total blood volume. Rapid losses of large quantities of blood during cannulation as occurs on occasion, or accidental injury to major vessels in the preparation for perfusion, may prejudice the outcome if fast and accurate replacement is not carried out prior to the total body bypass. Compensated Ifypovolemia.-In considering the efforts to safeguard the surgical patient against the hemodynamic changes brought about by over- or undertransfusion, attention should be directed to the possible danger inherent in compensated hypovolemia. Recent experiment of ours had shown that potassium excretion is impaired in compensated hypovolemia even though blood pressure and pulse rates remain unchanged. During compensated hypovolemia in animals, serum potassium levels will rise with infusions of hyperkalemic blood (bank blood). This rise does not occur in normovolemic animals. The rise of serum potassium exposes the animals to the possibility of cardiac arrest. These experimental observations confirm the effort that blood loss be replaced quantitatively as it is lost.
In Conclusion.-The feeling is expressed that the instantaneous and continuous determination of operative blood loss gives the surgeon the assurance that the patient's hemodynamics will not undergo sudden collapse and that the patient will not be exposed to biochemical changes making him susceptible to cardiac arrest because an exact replacement is made as blood is lost. The maintenance of hemodynamic equilibrium enhances greatly the execution of the purpose of surgery and safeguards the patient from measures which are necessitated under the duress of hemorrhage. SUMMARY
Instantaneous and continuous determination of operative blood loss was carried out in ·62 major thoracic procedures utilizing an apparatus, the blood loss monitor, based on the principle of electrical conductivity of the blood.
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BLOOD LOSS DETERMINATION DURING SURGERY
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Results are tabulated. Pathophysiology of response to blood loss has been discussed. The method proved to be simple, reliable, accurate, and extremely useful. ADDENDUM Since this report was submitted, the blood loss monitor was used in 57 additional major thoracic and cardiac operations. In none of the patients did shock occur during or after the completion of surgery, and in no instance was it necessary to use additional blood replacement beyond the amount indicated by the monitor during the surgical procedure. REFEREKCES
1. Ebert, R. V., Stead, E. A., and Gibson, .J. G.: Response of Normal Subjects to Acute Blood Loss, Arch. Int. Med. 68: 578, 1941. 2. Barcroft, H., Edholm, O. G., McMichael, .J., and Sharpey-Schafer, E. P.: Post Haemorrhagic Fainting, Lancet 1: 94, 1944. 3. Gatch, W. D., and Little, W. D.: Account of Blood Loss During Some of the More Common Operations, J. A. M. A. 83: 1075, 1924. 4. Wangenstcen, O. H.: The Controlled Administration of Fluid to Surgical Patients Ineluding Description of Gravimetric Methods of Determining Status of Hydration and Blood Loss During Operation, Minnesota Med. 25: 783-789, 1942. 5. White, M. L., and Buxton, R. IV.: Blood Loss in Thoracic Operations, J. THORACIC SURG. 12: 198, 1942. 6. Mil]('r, B. J., Gibbon, J. H., Jr., aild Allbritten, F. F., .Jr.: Blood Volume and Extracellular Fluid Changes During Thoracic Operations, J. THORACIC SURG. 18: 605, 1949. 7. LeVeen, H. H., and Rubricius, J. L.: Continuous, Automatic, Electronic Determinations of Operative Blood Loss, Surg. Gynec. & Obst. 106: 368, 1958. 8. Thornton, T. F., Adams, IV. E., Bryant, .J. E., and Carlton, L. M.: The Use of 'Vhole Blood Transfusions in Resections of the Lung, J. 'fHORACIC SURG. 14: 176, 1945. 9. Gibson, J. G., and Evans, IV. A.: Clinical Studies of Blood Volume, .J. Clin, Invest. 16: 301, 1937. DISCUSSION
DR. KLOPSTOCK.-In closing, I would like to show a short motion picture to demonstrate the blood loss monitor in simulated action. Here you see the apparatus with the dial face registering blood loss up to 8,000 c.c, Before using, a point is being tested. Now 1,000 e.c, of blood is delivered into the tub, watching the dial you see that it instantly registers 1,000 c.e, Then the content of the suction bottle, containing 450 c.c, of blood, is suctioned into the tub and you can notice that the registered total is now 1,450 c.c. Bloody sponges and pads are now dropped ino the tub, registering an additional 200 c.c.-altogether 1,650 c.c. of blood loss. Excessive foam formation in the tub solution is prevented by addition of an antifoam agent. Thank you.
procedures expand, the volume of operative blood loss increases, necessitating replacement of larger and larger amounts of blood. Anatomic structures dealt with in thoracic and cardiovascular surgery carry the risk of brisk hemorrhage on occasions and the demand of speedy restoration of the circulating blood volume. How then may one best maintain an adequate blood volume and at the same time prevent undertransfusion or eireulatory overloading? The work of Ebert and Stead- clearly indicates that during the course of blood loss in normal donors there is no gradual decrease in blood pressure and pulse rate. These authors state, "the onset of collapse was sudden. Until it occurred, the subject had no complaints. In three subjects collapse developed from 1 to 4 minutes after venous suction was completed. The compensatory mechanism appeared to break down suddenly cven though no more blood was being removed and the position of the subject had not been changed." This fact is well illustrated by a diagram which has been adapted from Barcroft and others" (Fig. 1) to demonstrate the changes in vital signs during the brisk hemorrhage in a normal donor. The blood pressure which starts in the neighborhood of 120 does not fall, the pulse rate rises but little, and yet the cardiac output continuously diminishes. It is only when compensation fails that the blood pressure drops suddenly. This shows that the blood pressure and the pulse rate cannot be relied upon as an index of adequate replacement. Neither the rise in pulse rate nor the fall in systolic pressure makes its appearance until the volume of blood loss is greater than can be compensated for by vasoconstriction. This usually does not occur until after 800 to 1,500 c.c, of blood is lost, if the From the Department of Surgery, Veterans Administration Hospital, Brooklyn, N. Y., and State University of New York, Downstate Medical Center, Brooklyn, N. Y. Read at the Thirty-ninth Annual Meeting of The American Association for Thoracic Surgery at Los Angeles. Calif., April 21-23, 1959. ·Chief, Thoracic Surgical Section, Veterans Administration Hospital, Brooklyn, N. Y., and Clinical Associate Professor of Surgery, N. Y. S. U. ··Chief, Surgical Service, Veterans Administration Hospital, Brooklyn, N. Y., and Associate Professor of Surgery, N. Y. S. U. ···Resident, Surgical Department, Veterans Administration Hospital, Brooklyn, N. Y.
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BLOOD LOsS DETERMINATION DURING SURGERY
VoL 38, No.6
December. 1959
patient is a well nourished and hydrated adult. Although venous pressure is of some value in determining the extent of blood loss, it becomes valueless during rapid bleeding and rapid replacement. During severe hemorrhage the sudden replacement of blood may fail to bring about a recovery in the hemodynamic alterations even when replacement has been of the proper amount. There have been various explanations for this failure of transfusion to prevent the disturbances in hemodynamics, some of which have been ascribed to the high citrate concentration of bank blood. The citrate in blood enhances the action of potassium by removing its ionic antagonist, the calcium. The potassium concentration of bank blood rises to 25 mEq. per liter by the end of 2 weeks. The rapid infusion of this bank blood may induce cardiac arrest or a state not unlike that of forward circulatory failure. It is under these circumstances that
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III 0: W I...J
Venesection IOBOe. em
---........................
80 12
w 0:
......
:::>
-.............
C.O.
J:_
100
Faint
RAP.
8
"w UJa.
............
.......................-....
. _ .__ - - - - -
10::: _ ww o:z Q. -
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6
6
~ ~
.
0:-
:::>
4
4,...;
o
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0:
MINUTE 5
Fig. l.-The course of events during rapid venous section of a normal donor is charted. Blood pressure (B.P.) falls precipitously from 120 to 40 mm. Hg. The heart rate (H.R.) does not rise above 100. The cardiac output (0.0.) falls continuously. The total peripheral resistance (T.P.R.) rises until decompensation occurs. Right auricular pressure (R.A.P.) falls continuously during the bleeding.
venous pressure will fail to differentiate between overtransfusion and forward circulatory failure induced by high potassium concentration of bank blood. It is, therefore, obvious that if accidents are to be avoided during surgery entailing massive blood loss that the amount of loss must be continuously measured during the operative procedure and exact replacement made for the amount which is lost. Since the first study of blood loss during some of the most common operations was reported by Gatch and Little" in 1924, many investigators have made extensive measurements of operative blood loss in the various fields of surgery
748
KLOPS1'OCK, LE VEEN, LEVITAN
1.Thoracic and Cardiovas. Sura.
and concluded that volume lost was always greater than the surgeon estimated and that the circulatory volume may be decreased considerably before clinical shock is noted. Great credit should go to Wangensteen- for having suggested (1942) the relatively simple and accurate method for determining operative blood loss as it occurs by weighing the dry sponges before and after their use and thus calculating the blood lost during surgery. In the field of thoracic surgery, White and Buxton," then Miller, Gibbon, and Allbrit.ten," made very valuable studies of blood loss during the various major thoracic procedures. Gibbon" and his associates pointed out that they were unable to estimate the amount of blood which had been lost and the amount which should be replaced by observing the vital circulatory signs. Operative blood loss has previously been determined by both the gravimetric and the colorimetric methods. Blood volume studies were done by the dye dilution method, according to Gibson and Evans," and by radioactive tagging of blood components, and the blood loss has been calculated in these ways. However valuable these methods are, they are not very suitable for the routine and everyday evaluation of blood loss in the operating room when extensive procedures of long duration are carried out. The possibility of using the phenomenon of electrical conductivity in the determination of operative blood loss has been investigated by Harry H. LeVeen. 7 The conductivity method is based on the fact that blood.is a solution of almost constant electrolyte composition. Even in "low salt syndrome" and other more serious disease states, the total sodium does not vary by more than 10 to 20 c.c. mEq. per liter. The extent of blood loss can therefore be assessed by measuring the quantity of lost electrolytes. The electrical resistance of a solution decreases with increasing electrolyte concentration. More concentrated solutions of electrolyte will allow for greater passage of current according to Ohm's law. If blood is added to water in varying concentrations, a direct proportional relationship between concentration of blood and conductance results. Since small changes in conductance can be accurately measured with a Wheatstone bridge, the change in conductance produced by the the addition of blood to known volume of water can be determined precisely. With a suitable Wheatstone bridge and proper temperature compensation, determinations are accurate to 0.5 per cent. LaVeen," utilizing the discussed principles, carried out extensive preliminary experiments and devised an apparatus, the blood loss monitor, which calculates and instantaneously registers all blood delivered into it. DESCRIPTION OF THE BLOOD LOSS MONITOR
The apparatus consists of a large stainless steel tub with an agitator which continuously extracts the electrolytes from the sponges and clots. A suction pump transfers blood from the operating table directly into the tub (Fig. 2). This procedure makes possible the addition of blood loss taken up via suction as well as from bloody sponges. Since conductivity increases with increasing temperature of the solution, automatic temperature compensation was
Vol. 38, No.6
December, 1959
BWOD LOSS DETERMINATION DURING SURGERY
749
accomplished by introducing a thermistor into one arm of the conductivity bridge. The thermistor assumes the temperature of the water in the reservior and changes the resistance of one arm in the bridge to compensate for the decreasing resistance of the solution at increased temperatures, It was desirable to have a direct reading instrument which would obviate the difficulties of manually balancing the conductivity bridge. Hence, a servomechanism was coupled with the conductivity bridge. The servomotor continuously brings the bridge to the null balance point. Instantaneous and continuous detection of conductivity changes are made. The conductivity bridge and cell must be specially constructed to operate on low voltages in order to minimize polarization and, at the same time, maintain its sensitivity. All components of the machine are constructed to meet explosion proof requirements
Fig. 2.-A photograph of the blood loss monitor is shown in simulated use. The bloody sponges are dropped in the open tub. The suction is connected to the side of the apparatus. The dial face can be seen.
for use in an operating room. 'I'he bridge is calibrated in cubic centimeters of blood rather than in solution conductance (the unit of electric conductivity) Blood loss is measured in increments of 100 c.c. up to 8,000 c.c. and with possible estimate of 25 to 50 c.c, within the increment. There is also an arrangement to measure small volume of blood loss from 0 to 800 c.c. to be used in surgery of children. This dial can be read with an accuracy to 20 coco and estimated to 10 c.c. within the increment (Fig. 3) This range can be put into operation by turning the proper switch. A centrifugal pump empties the tub following usage and the 0
0
750
KLOPSTOCK, LE VE E N, LEVITAN
J. Thoracic an d Cardiovas. Surg.
t ub can h e rapidly emp t ied into a regular sink and refilled so that losses g rea ter th an 8,000 c.c. can be measured. The machine is clea ned with a chlorin ated det e r gent foll owing us e a n d rinsed wit h t a p water . A st a inless steel mea sure is u sed to m ea sure t he initial quantit y of tap wa t e r placed in the tub. F'i xed resistances with push but ton s a re in cluded so t hat th e
o
....... CHILD
CHECK "'~
....... ADULT
Fig. 3.-The dial face t ogether with the range switch is illustrated In detail. switch Is in the "a dult" positi on readings a re mad e on the oute r circula r scale. switch is In the "ch ild" positi on the inn er cir cula r sc a le Is used for reading.
When the W hen the
POWER SUPPLY
Fi g. 4.- Sche matlc di a gram of the a utoma t ic blood loss meter. A measured volume of d is t illed water ( 25,000 c.c.) is a dded to the tub. An a gitato r ex t r act s elect r olytes f rom the s pon ges, la p pads. a nd clots. A s ucti on appara t us t ransf e rs blood from the ope rati ve site to the tub, Auto ma tic temperatu re com pensa tio n is accomplished with a thermistor wh ich form s one arm of this bri d ge. The cond uc t ivi ty cell is al so shown. A servomot or continuou sly keeps the brid ge a t the null balance po int . The dial of the meter Is calibrated directly In cubic centimeters of blood. Sponges a nd laparot omy pads a r e held in a stainless steel basket indicated by br oken lin e inside conta iner. ca lib r a t io n of t he ma chi ne ClUJ be pre-t es ted before usc. A nu ll b alance of 0 c.c. of bl ood is automatically a ccomplished by u sin g t ap w a t er of low con d uc tivity or di stilled water. Cor rect ion f or t he ini t ia l conductiv ity of t he water is then un necessary . A sche ma t ic dr awing of the instrumen t is sho wn i n F ig. 4.
Vol. 38, No.6
December, 1959
BLOOD LOSS DETERMINATION DURING SURGERY
751
Remarks.-It is evident that sodium chloride solutions cannot be used for irrigation purposes or to moisten sponges and pads. unless a definite measure of the amount of sodium chloride used is made and subtracted from the final total of indicated blood loss. We use a solution of 2.5 per cent glucose for moistening laparotomy pads for irrigation. Since glucose is a nonelectrolyte, it does not interfere with the readings. OBSERVATIONS
The blood loss monitor was used in 62 patients who underwent major thoracic and cardiovascular surgery.* In Table I, the observed minimum and maximum blood loss values are tabulated for each type of operation and the calculated averages are noted. These are approximately equal to those reported by other authors, notably by Miller, Gibbon, and Allbritten." Blood loss sustained up to the opening of the pleural cavity ranged 150 to 750 e.e. with an average of 364 C.c. It should be stressed that there was no need in any case for additional blood replacement after completion of the surgical procedure if blood replacement was made according to the indication on the monitor. In all cases there was less than 1.2 Gm. change in the hemoglobin value on the first to the fourth day as compared with preoperative values. Thornton and Adams" pointed out that the amount of hemoglobin tends to drop postoperatively in those cases where blood replacement has been inadequate. This postoperative drop in hemoglobin value described by Thornton and Adams did not occur in our cases in which the blood replacement was carried out under the guidance of the blood loss monitor. There were only 2 cases (No.1 and No.2) in which shock occurred during surgery, and these observations are described fully because of their study value. COMMENT ON ILLUSTRATIVE CASES
In this instance it was decided to compare the accuracy of the anesthetist's clinical estimate to blood loss registered by the monitor. Therefore, the "dial indication" of blood lost was unknown to him at the time vital signs had changed. I.-Lobectomy for Carcinoma With Chest Wall Involvement.The patient was a 39-year-old man with a round tumor in the right upper lobe. On exploration of a carcinoma, it appeared that it was anatomically resectable by means of an upper lobe resection, even though the tumor-bearing part of the lobe was densely adherent to the parietal pleura in a circumscribed area. In addition, the entire upper lobe was attached by vascular adhesions to the parietal pleura. Therefore an extrapleural dissection was carried out. This patient exhibited an unusual degree of oozing over a prolonged period of time. During the procedure, the degree of blood loss was not appreciated by the anesthetist until the vital signs changed. At this time 3,500 c.c. of blood loss was registered while only 2,000 c.c. had been replaced (Fig. 5). The known deficit was corrected gradually and the patient's condition returned to normal. Total blood loss and replacement for the operation was 7,000 c.c. In the postoperative period, no additional blood replacement was necessary. CASE
This observation illustrates the wide discrepancy between clinical impression and accurate measurement of blood loss. It is in such cases, when the blood loss is small hut continuous, that undertransfusion is common. ·See Addendum.
Miscellaneous chest wall procedures
TYPE OF SURGERY
4
NO. OF CASES -~
. 450
MINIMUM
2,200
AUTHOR "''''An
Loss
I
I DURING OPERATION
HOURS POSTOP.
I 48
SHOCK
MEASURED BY MONITOR
MILLER, GIBBON, ALLBRITTEN
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OPERATIVE BLOOD
3,500
1.
MAXIMUM """ ,..,... ....
TABLE ADDIT. REPLACEMENT 48 HR. POSTOP. REMARKS
t-:)
<:.l1
-:J
753
BLOOD LOSS DETERMINATION DURING SURGERY
Vol. 38, No.6
December, 1959
RIGHT LOBECTOMY CA WITH CHEST WALL INVOLVEMENT
t
TOTAL BLOOD LOSS
TOTAL 180
t
~ 3500ee
4500ee
7000ec
2000ee
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Fig. 5.-Illustrates not only the ease of management of a patient who during surgery had gradual blood loss of 7,000 c.c, with change in the hemodynamics but also the facility with which known large deficits can be readily corrected. CASE
2.-Mitral Comsnissurotomq.s-:
The patient was a 37-year-old white man with mitral stenosis. During the otherwise uneventful procedure there was a sudden loss of 1,200 c.c. of blood following tear of the left atrium and superior pulmonary vein. Blood pressure was unobtainable for a short period of time, but returned to normal after replacement of the indicated volume. The patient did well following surgery and no further blood replacement was needed (Fig. 6).
MITRAL COMMISSUROTOMY rTTOTAL BLOOD LOSS
I
2500ee 2500ce
TOOee 1900ee 2000ee BOOee lTOTAJ BLOOD REPLACED
180
Blood Pressure
lIJ 0::
:::> 140 (/) (/)
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60
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.-l
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Fig. 6.-Brisk blood loss precipitating shock during cardiac surgery is easily managed by monitoring and replacing the blood loss as it occurs.
754
J. Thoracic and
KLOPSTOCK, LE VEEN, LEVITAN
Cardiovas, Surg.
When blood loss is sudden and massive one may "get lost" in the management of replacement if it is based on clinical estimate. It is in such cases that overtransfusion, most commonly, and cardiac arrest, occasionally, are induced. The train of events substantiates also the experimental data on normal donors which indicate that vital signs do not change until considerable blood has been lost and only then they change suddenly.
H ypothermia.The increasing use of hypothermia poses problems for both surgeon and anesthesiologist. Not only does hypothermia render the vital signs valueless, but it also enhances the tendency toward cardiac arrest. During hypothermia, RESECTION OF ANEURYSM OF THORACIC AORTA WITH HYPOTHERMIA
~ 96~
~ 92 a: w 88 Q.
~ 84 l-
80 TOTAL TOTAL
180
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UI UI
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w
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{NO SUODEN LOSS;
:> 140
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I A.M.9
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Fig. 7.-Monitored blood loss and replacement during lO-hour hypothermic vascular surgery is graphically shown.
patients tolerate blood loss very poorly and the blood volume is restored very slowly after hemorrhage. This is partly brought about by a fall in the osmotic pressure of the plasma protein during hypothermia. Under these circumstances fluid cannot be rapidly mobilized from the tissue spaces. The instantaneous determination of blood loss was of considerable aid not only in thoracic surgery, but in all surgery performed with hypothermia. The following case report illustrates the usefulness of monitored blood loss in cardiovascular surgery carried out under hypothermia with necessarily hypotensive blood pressure levels and altered pulse rate. CASE
3.-Excision and Repbaoemcnt of Descending Thoracic Aorta.-
The patient was a 42-year-old white man with a large fusiform aneurysm of the descending thoracic aorta. At exploration the dilatation was found to extend from just distal to the left subclavian artery to a point just above the diaphragm. Under hypothermia a
BLOOD LOSS DETERMINATION DURING SURGERY
Vol. 38, No.6
December, 1959
755
Teflon prosthesis was used to bypass the aneurysm which was then resected; the prosthesis was left as a permanent bypass. There was no dramatic blood loss during the 10-hour procedure, but after replacing the volumes of blood indicated by the monitor, it was found that 6,200 c.c. of blood had been lost by continual ooze. The patient had an uneventful postoperative course and no further blood replacement was necessary (Fig. 7).
In the properly monitered case, blood deficit and overtransfusion do not occur if loss and replacement are checked periodically during the course of prolonged surgery. Hourly check should be considered the minimum interval during the uneventful progress of an operation. A typical chart of monitored blood loss is shown in Fig. 8. RIGHT
UPPER LOBECTOMY TYPICAL CASE rTOr
L
Bt
OOD
rSSr-r-:J
150cc450cc IOOOcc 1650cc2100CC2700cc3000CC
10CC t TOTAL BLOOD
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3
t
2250cc 2900cc 15rOCC 2600cc
1
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_
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~ 100
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9
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______'
P.M.
TIME
Fig. B.-The matching of blood replacement to blood loss is shown in a typical intrathoracic surgical procedure. GENERAL COMMENTS
In the foregoing, data are presented to document the value of an apparatus, the blood loss monitor, for accurate determination of blood loss during surgery as it occurs. The construction and function of the apparatus is based on the fact that the blood is a solution of almost constant electrolyte composition. The extent of the blood loss is assessed by measuring the quantity of lost electrolytes. _ Since the characteristics of blood as an electrolyte are utilized as a measurement of blood, all the factors affecting conductivity in blood must be reckoned with.
Nonelectrolyte in high enough concentration will effect a reduction in conductivity. The usual concentration of glucose and nonprotein nitrogen in blood do not produce a perceptible change. Serum protein and hemoglobin do influence conductivity in an ideal way. For each gram per cent deficit in plasma
KLOPSTOCK, LE VEEN, LEVITAN
756
J. Thoracic and Cardiovas. Surg.
protein, conductivity increases approximately 2 per cent. A blood loss of 100 e.e. in a patient with a gram per cent deficit in plasma protein would appear as a loss of 102 C.c. This would cause the patient to be overtransfused by 2 per cent. A change in hematocrit from 50 to 5 will register approximately 20 per cent increase in loss. An anemia of 50 per cent would bring about an overreplacement of blood loss by an amount slightly in excess of 10 per cent. The method makes moderate corrections for severe hypoproteinemia and anemia. Open Ifeart Surgery.- vVe have not yet had the opportunity to usc the blood loss monitor in open heart surgery, but it seems apparent that such an apparatus could be of inestimable value. The accurate determination of the blood lost before the perfusion begins could be accomplished with ease. During perfusion all blood lost from the' oxygenator-patient-circuit must be accurately known so that correct volume of blood may be maintained in the patient and the perfusion terminated with the patient in normovolcmie state. In infants, of course, this assumes even greater importance since small amounts of blood represent larger proportions of total blood volume. Rapid losses of large quantities of blood during cannulation as occurs on occasion, or accidental injury to major vessels in the preparation for perfusion, may prejudice the outcome if fast and accurate replacement is not carried out prior to the total body bypass. Compensated Ifypovolemia.-In considering the efforts to safeguard the surgical patient against the hemodynamic changes brought about by over- or undertransfusion, attention should be directed to the possible danger inherent in compensated hypovolemia. Recent experiment of ours had shown that potassium excretion is impaired in compensated hypovolemia even though blood pressure and pulse rates remain unchanged. During compensated hypovolemia in animals, serum potassium levels will rise with infusions of hyperkalemic blood (bank blood). This rise does not occur in normovolemic animals. The rise of serum potassium exposes the animals to the possibility of cardiac arrest. These experimental observations confirm the effort that blood loss be replaced quantitatively as it is lost.
In Conclusion.-The feeling is expressed that the instantaneous and continuous determination of operative blood loss gives the surgeon the assurance that the patient's hemodynamics will not undergo sudden collapse and that the patient will not be exposed to biochemical changes making him susceptible to cardiac arrest because an exact replacement is made as blood is lost. The maintenance of hemodynamic equilibrium enhances greatly the execution of the purpose of surgery and safeguards the patient from measures which are necessitated under the duress of hemorrhage. SUMMARY
Instantaneous and continuous determination of operative blood loss was carried out in ·62 major thoracic procedures utilizing an apparatus, the blood loss monitor, based on the principle of electrical conductivity of the blood.
Vol. 38, No.6 December, 1959
BLOOD LOSS DETERMINATION DURING SURGERY
757
Results are tabulated. Pathophysiology of response to blood loss has been discussed. The method proved to be simple, reliable, accurate, and extremely useful. ADDENDUM Since this report was submitted, the blood loss monitor was used in 57 additional major thoracic and cardiac operations. In none of the patients did shock occur during or after the completion of surgery, and in no instance was it necessary to use additional blood replacement beyond the amount indicated by the monitor during the surgical procedure. REFEREKCES
1. Ebert, R. V., Stead, E. A., and Gibson, .J. G.: Response of Normal Subjects to Acute Blood Loss, Arch. Int. Med. 68: 578, 1941. 2. Barcroft, H., Edholm, O. G., McMichael, .J., and Sharpey-Schafer, E. P.: Post Haemorrhagic Fainting, Lancet 1: 94, 1944. 3. Gatch, W. D., and Little, W. D.: Account of Blood Loss During Some of the More Common Operations, J. A. M. A. 83: 1075, 1924. 4. Wangenstcen, O. H.: The Controlled Administration of Fluid to Surgical Patients Ineluding Description of Gravimetric Methods of Determining Status of Hydration and Blood Loss During Operation, Minnesota Med. 25: 783-789, 1942. 5. White, M. L., and Buxton, R. IV.: Blood Loss in Thoracic Operations, J. THORACIC SURG. 12: 198, 1942. 6. Mil]('r, B. J., Gibbon, J. H., Jr., aild Allbritten, F. F., .Jr.: Blood Volume and Extracellular Fluid Changes During Thoracic Operations, J. THORACIC SURG. 18: 605, 1949. 7. LeVeen, H. H., and Rubricius, J. L.: Continuous, Automatic, Electronic Determinations of Operative Blood Loss, Surg. Gynec. & Obst. 106: 368, 1958. 8. Thornton, T. F., Adams, IV. E., Bryant, .J. E., and Carlton, L. M.: The Use of 'Vhole Blood Transfusions in Resections of the Lung, J. 'fHORACIC SURG. 14: 176, 1945. 9. Gibson, J. G., and Evans, IV. A.: Clinical Studies of Blood Volume, .J. Clin, Invest. 16: 301, 1937. DISCUSSION
DR. KLOPSTOCK.-In closing, I would like to show a short motion picture to demonstrate the blood loss monitor in simulated action. Here you see the apparatus with the dial face registering blood loss up to 8,000 c.c, Before using, a point is being tested. Now 1,000 e.c, of blood is delivered into the tub, watching the dial you see that it instantly registers 1,000 c.e, Then the content of the suction bottle, containing 450 c.c, of blood, is suctioned into the tub and you can notice that the registered total is now 1,450 c.c. Bloody sponges and pads are now dropped ino the tub, registering an additional 200 c.c.-altogether 1,650 c.c. of blood loss. Excessive foam formation in the tub solution is prevented by addition of an antifoam agent. Thank you.